Spindle drive assembly, vehicle flap with a spindle drive assembly and method for installing a spindle drive assembly

ABSTRACT

A spindle drive assembly for opening and/or closing a vehicle flap is described. It has a spindle drive assembly housing extending along a spindle drive axis and having, between its axial ends, a stop section acting axially on both sides. A motor gear unit is arranged on a first side of the stop section and a spindle unit is arranged on a second side of the stop section. Furthermore, a vehicle flap with such a spindle drive assembly is presented. In addition, a method of assembling a spindle drive assembly is presented.

The invention relates to a spindle drive assembly for opening and/orclosing a vehicle flap.

The invention further relates to a vehicle flap, in particular a vehiclehatch or tailgate or a vehicle trunk lid, with such a spindle driveassembly.

In addition, the invention relates to a method of assembling a spindledrive assembly of the above-mentioned type.

Vehicle flaps and spindle drive assemblies of the type initiallymentioned are known from the prior art.

The known spindle drive assemblies generally comprise an electricspindle drive by means of which the associated vehicle flap can beopened and/or closed. This means that a user of an associated vehicle nolonger needs to carry out the opening and closing manually. The useronly needs to send an open or close command to the spindle driveassembly, which he or she can do, for example, via a radio remotecontrol or via a switch arranged in the vehicle. A foot switch which isarranged on the outside of the vehicle and can operate without contactcan also be used.

In order to protect in particular the electrical components of thespindle drive assembly from environmental influences such as, e.g.,moisture and dust, the spindle drive assemblies are usually encased whenthey are mounted to a vehicle flap.

In the field of the manufacture of spindle drive assemblies, the aim isto keep the assembly of the spindle drive assembly as simple andcost-effective as possible. However, this causes a conflict ofobjectives with a reliable encasing or enclosure, so that a spindledrive assembly that is simple and cost-effective to assemble generallyoffers only moderate protection from environmental influences.

The object of the invention is to overcome this conflict of objectivesand to indicate a spindle drive assembly which can be assembled in asimple and cost-effective manner and also provides a particularlyeffective protection of the spindle drive assembly components againstenvironmental influences.

The object is achieved by a spindle drive assembly of the type initiallymentioned, in which a spindle drive assembly housing extends along aspindle drive axis and the spindle drive assembly housing includes,between its axial ends, a stop section acting axially on both sides, amotor gear unit being arranged on a first axial side of the stop sectionand a spindle unit being arranged on a second axial side of the stopsection opposite the first axial side. The motor gear unit here includesan electric spindle drive motor and a gearing coupled thereto. Inaddition, it may optionally also comprise a brake, one or more sensorsand/or an overload safety device. The spindle unit comprises at leastone spindle and a spindle nut coupled thereto. The stop section providesfor a defined position of the motor gear unit and the spindle unitwithin the spindle drive assembly housing. This applies both duringoperation and during assembly. The spindle drive assembly housing ispreferably tubular and has a substantially circular cross-section.Therefore, that part in which the motor gear unit and the spindle unitare seated can preferably be manufactured in one piece, so that thesecomponents are particularly well protected against environmentalinfluences. This results from the absence of contact surfaces or contactlines between different components of the spindle drive assembly housingin this region. Such contact surfaces or lines constitute weak pointswith respect to undesirable environmental influences. In addition, sucha spindle drive assembly is particularly simply constructed andtherefore simple and cost-effective to assemble.

Preferably, the spindle drive assembly housing comprises a housing cap,which closes the spindle drive assembly housing on the motor gear unitside, the housing cap being more particularly laser welded inside thespindle drive assembly housing. Such a housing cap provides aparticularly simple closure of the spindle drive assembly housing.Furthermore, the housing cap reliably seals the spindle drive assemblyhousing and in this way ensures an effective protection of thecomponents contained in the spindle drive assembly housing against anyundesirable environmental influences. This is particularly the case ifthe housing cap is laser welded. An associated laser weld seamconstitutes a watertight and dustproof connection. Preferably, the laserweld seam here fully surrounds a circumference of the housing cap, sothat the housing cap reliably seals the end of the spindle driveassembly housing. It is further preferred that the laser weld seam iscircumferential through at least 361 degrees. This provides aparticularly highly reliable protection against undesirableenvironmental influences. Thus, the spindle drive assembly housing iswatertight.

Preferably, a mechanical interface to a vehicle body is arranged on thehousing cap and includes ball sockets or stop means, for example. Thehousing cap may also have an electrical interface provided thereon,which includes a cable lead-through, for example.

According to one embodiment, the motor gear unit is supported in thespindle drive assembly housing so as to be rotationally fixed withrespect to the spindle drive axis, in particular wherein the motor gearunit is supported in the spindle drive assembly housing by means of adamping element or by means of a plurality of damping elements.Preferably, the motor gear unit is supported in the spindle driveassembly housing by means of an interlocking fit. In this way, therotationally fixed mounting is achieved by simply inserting the motorgear unit into the spindle drive assembly housing. The assembly processis therefore particularly simple. Here, the rotationally fixed mountingof the motor gear unit serves for torque support.

A respective damping element, e.g. made from an elastomer, may beprovided at each of the two axial ends of the motor gear unit, theaforementioned interlocking fit being implemented by means of thedamping element. Accordingly, the driving torque of the motor gear unitis supported axially at the front and axially at the rear.

The spindle unit may comprise a guide tube fastened in the spindle driveassembly housing, in particular wherein the guide tube and the spindledrive assembly housing are laser welded. The guide tube ensures aprecise and reliable guidance of the spindle nut. It may be in the formof a plain bearing bush. The fastening of the guide tube to the spindledrive assembly housing is preferably made to be watertight, so thatthere is no possibility of undesirable environmental impact on thecomponents of the spindle drive assembly at this point. This isparticularly the case if the guide tube and the spindle drive assemblyhousing are laser welded. An associated laser weld seam preferably isfully circumferential and, more preferred, is circumferential through atleast 361 degrees, thus effecting a particularly reliable sealing of thespindle drive assembly housing against any undesirable environmentalinfluences. In particular, the spindle drive assembly housing iswatertight.

Preferably, the guide tube is made from a plastic material.

Advantageously, the stop section is manufactured in one piece with thespindle drive assembly housing. The spindle drive assembly housing cantherefore be manufactured with particularly little effort and atparticularly low cost.

The spindle drive assembly housing may be produced by injection molding,for example.

The spindle drive assembly housing is preferably made from plastic. Thismaterial is watertight and dustproof. It is therefore particularly wellsuited for protecting the components of the spindle drive assembly fromenvironmental influences. Also, plastic materials can be processedeasily and cost-effectively using standard machines, so that the spindledrive assembly can also be manufactured simply and cost-effectively.

Furthermore, the object is achieved by a vehicle flap of the typeinitially mentioned, in particular a vehicle hatch or tailgate orvehicle trunk lid, which includes a spindle drive assembly according tothe invention. Since the spindle drive assembly is structured in asimple and cost-effective manner, a vehicle flap fitted with it isconsequently also structured to be comparatively simple andcost-effective. Moreover, such a vehicle flap is particularly reliablein operation because the spindle drive assembly is particularly wellprotected against undesirable environmental influences.

In addition to the above-mentioned vehicle flaps, luggage flaps ortailgates of sport utility vehicles or commercial vehicles may also befitted with a spindle drive assembly according to the invention. Thesame applies to engine hoods and vehicle front gates.

Additionally, the object is achieved by a method of the type initiallymentioned, which includes the steps of:

-   -   (a) providing a spindle drive assembly housing extending along a        spindle drive axis;    -   (b) inserting a motor gear unit into the spindle drive assembly        housing starting from a first axial side of the spindle drive        assembly housing; and    -   (c) inserting a spindle unit into the spindle drive assembly        housing starting from a second axial side of the spindle drive        assembly housing opposite the first.

This means that the motor gear unit and the spindle unit are insertedinto the spindle drive assembly housing from opposite sides. The spindledrive assembly housing is therefore particularly well accessible forassembly. Furthermore, this allows the motor gear unit and the spindleunit to be inserted into the spindle drive assembly housing at the sametime or overlapping in time. As a result, assembly can be effectedparticularly quickly in time. All in all, a simple and cost-effectiveassembly is thus achieved.

A stop section acting axially on both sides may be provided at thespindle drive assembly housing and the motor gear unit may be placedagainst a first axial side of the stop section. In this way, the motorgear unit is simply and reliably positioned in the spindle driveassembly housing. Any subsequent alignment or adjustment is notnecessary.

In an alternative, the motor gear unit is mounted in the spindle driveassembly housing in a rotationally fixed manner, in particular whereinthe motor gear unit is mounted in the spindle drive assembly housingwith an interlocking fit. Here, the interlocking mounting may compriseone or more damping elements. In this case, first the damping elementsare fixed on the motor gear unit and then the component assembly made upof the motor gear unit and the damping elements is mounted in thespindle drive assembly housing. The interlocking mounting allowssubsequent fastening steps, in particular those serving to support adriving torque of the motor gear unit, to be dispensed with.

Preferably, a first damping element is fixed to an end of the motor gearunit that is axially at the front and a second damping element is fixedto an end that is axially at the rear.

The damping elements are made from an elastomer, for example.

In one embodiment, a stop section acting axially on both sides isprovided at the spindle drive assembly housing, and the spindle unit isplaced against a second axial side of the stop section opposite thefirst axial side. In this way, the spindle unit is positioned simply andreliably within the spindle drive assembly housing. Any subsequentalignment or adjustment is not necessary here, either.

Preferably, the spindle unit is fastened to the spindle drive assemblyhousing, in particular wherein the spindle unit is laser welded to thespindle drive assembly housing. In this way, the spindle unit isreliably held in its intended position. In addition, the laser weld seamproduces a seal against any undesirable environmental influences, whichin particular is watertight. Preferably, the laser weld seam is fullycircumferential. More preferably, it encircles the circumference throughat least 361 degrees.

A guide tube comprised by the spindle unit may also be fastened to thespindle drive assembly housing, in particular wherein the guide tube islaser welded to the spindle drive assembly housing.

In one variant, a housing cap is placed on the spindle drive assemblyhousing on the motor gear unit side, so that the housing cap closes thespindle drive assembly housing.

In this context, the housing cap may be fastened inside the spindledrive assembly housing, in particular laser welded inside the spindledrive assembly housing.

The invention will be discussed below with reference to an exemplaryembodiment shown in the accompanying drawings, in which:

FIG. 1 schematically shows a vehicle flap according to the inventionwith a spindle drive assembly according to the invention that isassembled by means of a method according to the invention;

FIG. 2 shows the spindle drive assembly from FIG. 1 in a schematicsectional view;

FIG. 3 shows the spindle drive assembly from FIG. 1 in an explodedrepresentation;

FIG. 4 shows the spindle drive assembly from FIG. 1 in a sectionaldetail view;

FIG. 5 shows a spindle drive motor of the spindle drive assembly fromFIG. 1 in a perspective view;

FIG. 6 schematically shows the interaction of the spindle drive motorfrom FIG. 5 with a spindle drive assembly housing in a partly sectionalillustration;

FIG. 7 schematically shows an end view of the spindle drive motor fromFIGS. 5 and 6 and of a housing cap adapted to be connected with thespindle drive motor;

FIG. 8 shows an exploded illustration of a two-stage epicyclic gearingof the spindle drive assembly from FIG. 1, which can be assembled bymeans of a method according to the invention;

FIG. 9 shows a further exploded illustration of the two-stage epicyclicgearing of the spindle drive assembly from FIG. 1, with the epicyclicgearing partly assembled by means of a method according to theinvention;

FIG. 10 shows an exploded illustration of the spindle drive assemblyfrom FIG. 1, comprising a two-stage epicyclic gearing, a coupling, ahysteresis brake and a spindle drive motor;

FIG. 11 shows a spindle unit of the spindle drive assembly from FIG. 1in an exploded illustration;

FIG. 12 shows a detail of the spindle unit from FIG. 11;

FIG. 13 shows a detail of the spindle drive assembly from FIG. 1 in asectional illustration; and

FIG. 14 shows a further detail of the spindle drive assembly from FIG. 1in a sectional illustration.

FIG. 1 shows a vehicle flap 10, which in the present case is a vehiclehatch or liftgate, having a spindle drive assembly 12 by means of whichthe vehicle flap 10 can be opened and/or closed.

The spindle drive assembly 12 comprises a spindle drive assembly housing14 that extends along a spindle drive axis 16.

As can be seen in particular by reference to FIG. 2, a motor gear unit18, only schematically illustrated in FIG. 2, and a spindle unit 20,also only schematically illustrated in FIG. 2, are arranged in thespindle drive assembly housing 14.

The spindle drive assembly housing 14 here comprises, between its axialends 14 a, 14 b, a stop section 22 acting axially on both sides.

The motor gear unit 18 is arranged on a first axial side 22 a of thestop section 22 and the spindle unit 20 is arranged on a second axialside 22 b opposite the first axial side 22 a.

Both the motor gear unit 18 and the spindle unit 20 rest against thestop section 22.

In the illustrated embodiment (see in particular FIGS. 3 and 4), themotor gear unit 18 is supported in the spindle drive assembly housing 14by means of two damping elements 24 a, 24 b made from an elastomer.

In addition to a spindle 26 and a spindle nut 28 coupled thereto, thespindle unit 20 comprises a guide tube 30.

In the illustrated embodiment, the guide tube 30 is fastened to thespindle drive assembly housing 14. More precisely, the guide tube 30 islaser welded to the spindle drive assembly housing 14. The laser weldseam 32 is drawn in only schematically here.

The stop section 22 is produced in one piece with the spindle driveassembly housing 14.

Here, the spindle drive assembly housing 14 is made from a plasticmaterial.

In the present case, the stop section 22 is manufactured by injectionmolding the spindle drive assembly housing 14.

The spindle drive assembly housing 14 additionally comprises a housingcap 14 c. It closes the spindle drive assembly housing 14 on the motorgear unit side.

The housing cap 14 c and the spindle drive assembly housing 14 are laserwelded. The laser weld seam 34 is again drawn only schematically here.

The assembly of the spindle drive assembly 12 is performed as follows.

First, the spindle drive assembly housing 14 is provided.

Then the motor gear unit 18 is inserted into the spindle drive assemblyhousing 14 starting from a first axial side of the spindle driveassembly housing 14 on which, in the example shown, the axial end 14 bis located.

In doing so, the motor gear unit 18 is placed against the first axialside 22 a of the stop section 22.

The spindle unit 20 is inserted into the spindle drive assembly housing14 from a second axial side 22 b of the spindle drive assembly housing14 opposite to the first axial side thereof. In the illustratedembodiment, the axial end 14 a is located on this side.

The spindle unit 20 is placed against the second axial side 22 b of thestop section 22.

It is irrelevant to the assembly process whether first the motor gearunit 18 or first the spindle unit 20 is mounted to the spindle driveassembly housing 14. The motor gear unit 18 and the spindle unit 20 mayalso be mounted essentially simultaneously.

When the spindle unit 20 has been inserted in the spindle drive assemblyhousing 14, it is fastened in it. In the illustrated embodiment, thespindle unit 20 comprises a guide tube 30 that is fastened to thespindle drive assembly housing 14 by means of the laser weld seam 32.

That is, the spindle drive assembly housing 14 and the guide tube 30 arelaser welded.

Subsequently, the spindle drive assembly housing 14 is closed at its end14 b using a housing cap 14 c. In this context, the spindle driveassembly housing 14 is laser welded to the housing cap 14 c.

The motor gear unit 18 comprises a spindle drive motor 36, which iscoupled to a gearing 40 via a motor shaft 38.

FIGS. 5-7 show the spindle drive motor 36 in detail.

With the motor gear unit 18 arranged within the spindle drive assemblyhousing 14, the spindle drive motor 36 is also positioned within thespindle drive assembly housing 14. The motor shaft 38 here issubstantially coaxial with the spindle drive axis 16.

In addition, the spindle drive motor 36 and thus the motor gear unit 18are supported in the spindle drive assembly housing 14 so as to berotationally fixed with respect to the spindle drive axis 16 by means ofan interlocking fit.

More precisely, the spindle drive motor 36 is supported at the housingcap 14 c in a rotationally fixed manner by means of an interlocking fit,the housing cap being a component part of the spindle drive assemblyhousing 14.

The rotationally fixed mounting is provided here by means of a motorhousing 42 of the spindle drive motor 36.

In the illustrated embodiment, it has two anti-rotation projections 44a, 44 b provided thereon which, in the assembled state of the spindledrive motor 36 and thus also of the motor gear unit 18, extendsubstantially along the spindle drive axis 16.

In the present case, the anti-rotation projections 44 a, 44 b arecircular cylindrical, with the associated circular cylinder center axes46 a, 46 b extending substantially parallel to the spindle drive axis 16in the mounted state of the spindle drive motor 36.

The anti-rotation projections 44 a, 44 b are provided on an axial endside 48 of the spindle drive motor 36 facing away from the motor shaft38. In the assembled state, the anti-rotation projections 44 a, 44 b arethus positioned on a side of the spindle drive motor 36 opposite to thegearing 40.

In the assembled state, the anti-rotation projections 44 a, 44 b engagein associated recesses 50 a, 50 b provided on the spindle drive assemblyhousing 14.

In the illustrated embodiment, the recesses 50 a, 50 b are provided onthe housing cap 14 c.

More precisely, in the illustrated embodiment, the recesses 50 a, 50 bare provided on the damping element 24 b, which is connected to thehousing cap 14 c in a rotationally fixed manner.

As an alternative, the anti-rotation projections 44 a, 44 b may engagein the recesses 50 a, 50 b via elastic damping caps arranged on theanti-rotation projections 44 a, 44 b or via elastic damping elementsarranged in the recesses 50 a, 50 b.

As is apparent in particular by reference to FIG. 5, in the illustratedembodiment, besides the anti-rotation projections 44 a, 44 b, a firstelectrical power connection 52, a second electrical power connection 54and a sensor connection 56 are additionally provided on the axial endside 48 of the spindle drive motor 36.

FIGS. 8 and 9 show the gearing 40 in detail.

It can be seen here that the gearing 40 is a two-stage epicyclic gearing58.

In this context, it comprises a first epicyclic gearing stage 58 a,which is also referred to as motor-side or drive-side epicyclic gearingstage 58 a, and a second epicyclic gearing stage 58 b, which is alsoreferred to as spindle-side or driven-side epicyclic gearing stage 58 b.

The epicyclic gearing 58 has helical toothings. Both epicyclic gearingstages 58 a, 58 b have helical toothings in the same direction.

Moreover, the two-stage epicyclic gearing 58 comprises merely onesingle, singular planet carrier 60, which is thus part of both epicyclicgearing stages 58 a, 58 b.

Furthermore, both the motor-side epicyclic gearing stage 58 a and thespindle-side epicyclic gearing stage 58 b comprise an equal number ofplanet gears 62 a, 62 b. In the exemplary embodiment shown, each of theepicyclic gearing stages 58 a, 58 b comprises four planet gears 62 a, 62b.

One respective planet gear 62 a of the first epicyclic gearing stage 58a and one respective planet gear 62 b of the second epicyclic gearingstage 58 b are mounted on a shared planet gear pin 64.

The planet gears 62 a, 62 b mounted on a shared planet gear pin 64 areconnected to each other for joint rotation.

The epicyclic gearing 58 operates as follows.

The motor shaft 38 is rotationally coupled to a sun gear 66 of themotor-side epicyclic gearing stage 58 a. Thus, the sun gear 66constitutes the drive or torque input of the epicyclic gearing 58.

Since this coupling is effected via a clutch or coupling 68, strictlyspeaking a gearing input shaft 70 is coupled to the sun gear 66.However, it may be regarded as a continuation of the motor shaft 38.

In the illustrated embodiment, the coupling 68 is an Oldham coupling forcompensating an axial offset. FIG. 8 only shows a gearing-side couplingpart 69, which is connected with the gearing input shaft 70.

The sun gear 66 cooperates with the planet gears 62 a of the motor-sideepicyclic gearing stage 58 a, which in turn are coupled to a ring gear72 of the motor-side epicyclic gearing stage 58 a.

The ring gear 72 is mounted so as to be rotationally fixed and axiallyfixed in the spindle drive assembly housing 14 and/or in an epicyclicgearing housing 74. This means that the ring gear 72 is substantiallypositioned fixed in space.

The motor-side epicyclic gearing stage 58 a is coupled to thespindle-side epicyclic gearing stage 58 b both via the singular planetcarrier 60 and via the one-piece planet gears 62 a, 62 b.

Here, the spindle-side epicyclic gearing stage 58 b is constructedwithout a sun gear.

The planet gears 62 b of the spindle-side epicyclic gearing stage 58 bare only radially supported on an axial bearing extension 76 of the sungear shaft of the motor-side epicyclic gearing stage 58 a. The sun gearshaft here corresponds to the gearing input shaft 70.

The planet gears 62 b of the spindle-side epicyclic gearing stage 58 bare further coupled to a ring gear 78 of the spindle-side epicyclicgearing stage 58 b.

This ring gear 78 is rotationally coupled to the spindle 26 by means ofa coupling 80. The ring gear 78 is mounted for rotation in the spindledrive assembly housing 14 and/or in the epicyclic gearing housing 74.

The ring gear 78 thus constitutes the output or torque output of theepicyclic gearing 58.

The epicyclic gearing 58 can be assembled as follows.

First, all planet gears 62 a, 62 b of the two epicyclic gearing stages58 a, 58 b are fitted in the singular planet carrier 60.

Subsequently, the planet carrier 60 is inserted into the ring gear 72 ofthe drive-side epicyclic gearing stage 58 a or into the ring gear 78 ofthe driven-side epicyclic gearing stage 58 b.

Then, the respective other ring gear, that is, the ring gear 78 or thering gear 72, is placed on this component assembly.

Thereafter, the epicyclic gearing housing 74 is provided and connectedwith the ring gear 72.

In the illustrated embodiment, the epicyclic gearing housing 74 is laserwelded to the ring gear 72 in a lap joint. For this purpose, theepicyclic gearing housing 74 is laser light transmissive.

For the spindle drive assembly 12 to emit noises when operating that amotor vehicle user will perceive as pleasant, the ratio of the number ofteeth of each of the planet gears 62 a of the first epicyclic gearingstage 58 a to the number of teeth of each of the planet gears 62 b ofthe second epicyclic gearing stage 58 b is selected to be 2:1.

In the illustrated embodiment, each planet gear 62 a of the firstepicyclic gearing stage 58 a comprises twelve teeth and each planet gear62 b of the second epicyclic gearing stage 58 b comprises six teeth.

The ratio of 2:1 corresponds to the interval of an octave when it isbased on a ratio of sound frequencies.

Given that the sound frequency emitted by the first epicyclic gearingstage 58 a is decisively determined by the number of teeth of the planetgears 62 a of the first epicyclic gearing stage 58 a and the soundfrequency emitted by the second epicyclic gearing stage 58 b isdecisively determined by the number of teeth of the planet gears 62 b ofthe second epicyclic gearing stage 58 b, the spindle drive assembly 12thus emits sound frequencies in operation which form an octave. This isperceived as particularly pleasant by vehicle users.

In addition, a vehicle user will associate such pleasant noises with ahigh level of quality of spindle drive assembly 12.

Alternatively, the ratio of the number of teeth of each of the planetgears 62 a of the first epicyclic gearing stage and the number of teethof each of the planet gears 62 b of the second epicyclic gearing stagemay also be selected to be 3:2, 4:3, 5:4, or 6:5.

The emitted sound frequencies then form a fifth, a fourth, a major thirdor a minor third, respectively. These intervals are also perceived aspleasant by humans.

Generally speaking, the ratio of the number of teeth of each planet gear62 a of the first epicyclic gearing stage 58 a to the number of teeth ofeach planet gear 62 b of the second epicyclic gearing stage 58 b isselected such that, in operation, a first sound frequency that isemitted by the first epicyclic gearing stage 58 a differs by an integermultiple of a semitone from a second sound frequency that is emitted bythe second epicyclic gearing stage 58 b.

The preferred embodiment of the octave comprises twelve semitone steps,that of the fifth seven, that of the fourth five, that of the majorthird four and that of the minor third three.

The coupling of the spindle drive motor 36 to the gearing 40, moreprecisely to the two-stage epicyclic gearing 58, is illustrated indetail in FIG. 10. Here, the coupling 68 compensating an axial offsetand a hysteresis brake 82 are drivingly interposed between the spindledrive motor 36 and the gearing 40.

As already mentioned, the coupling 68 is an Oldham coupling andcomprises a coupling part 84 on the drive motor side and the couplingpart 69 on the gearing side (see FIG. 8).

The two coupling parts 69, 84 are connected to each other via anintermediate coupling part 86 such that the motor shaft 38 and thegearing input shaft 70 are connected to each other for joint rotation.

At the same time, when in the mounted state, the intermediate couplingpart 86 is displaceable in relation to the drive motor-side couplingpart 84 along a direction 88.

The gearing-side coupling part 69 is displaceable in relation to theintermediate coupling part 86 along a direction 90.

The direction 88 and the direction 90 are substantially orthogonal toeach other here. In this way, an axial offset between the motor shaft 38and the gearing input shaft 70 can be compensated in line with theoperating principle of an Oldham coupling.

The hysteresis brake 82 comprises a stationary hysteresis brakecomponent 92, which is fastened to the spindle drive assembly housing 14and/or to the epicyclic gearing housing 74.

Furthermore, the hysteresis brake 82 includes a rotatable hysteresisbrake component 94 rotationally coupled to the motor shaft 38.

The hysteresis brake component 94 is fastened to or integrated in thedrive motor-side coupling part 84. More particularly, the rotatablehysteresis brake component 94 is injected into the drive motor-sidecoupling part 84.

When the spindle drive assembly 12 is viewed perpendicularly to thespindle drive axis 16, the coupling 68 is arranged substantiallycompletely within the hysteresis brake 82 in the axial direction, inparticular within the stationary hysteresis brake component 92. Thestructure of the coupling 68 and the hysteresis brake 82 is thereforeespecially compact.

FIGS. 11-14 show the spindle unit 20 in detail.

Here, a stop assembly 96 arranged at one axial end of the spindle 26 isadapted to limit a mobility of the spindle nut 28 along the spindledrive axis 16. Specifically, in this way the spindle nut 28 is preventedfrom moving beyond the end of the spindle 26.

The stop assembly 96 comprises a plastically deformable energyabsorption component 97, which in the illustrated embodiment is in theform of an energy absorption sleeve 98, which surrounds the spindle 26substantially coaxially.

This means that the energy absorption sleeve 98 is mounted at thespindle 26.

The energy absorption sleeve 98 is arranged between a bearing washer 100on the spindle end side and the spindle nut 28 along the spindle driveaxis 16 (see in particular FIG. 14).

Moreover, a bearing member 102 is provided between the energy absorptionsleeve 98 and the bearing washer 100 to support the spindle 26 at thespindle drive assembly housing 14.

In addition, a thrust washer 104 that is axially displaceable on thespindle 26 is arranged between the energy absorption sleeve 98 and thespindle nut 28.

In the illustrated embodiment, both the bearing washer 100 and thethrust washer 104 are made of a metal material.

At each of its two axial ends, the energy absorption sleeve 98 has arespective collar 106 a, 106 b configured as a force introductioncollar.

A deformation section 108 adapted to be upset in the direction of thespindle drive axis 16 is positioned between the collars 106 a, 106 b.

In the illustrated embodiment, the deformation section includes only onesingle deformation portion. In alternative embodiments, however, it maycomprise several, in particular two, deformation portions, with bothdeformation portions being adapted to be upset in the direction of thespindle drive axis 16.

In a regular operation of the spindle drive assembly 12, the energyabsorption sleeve 98 is essentially plastically undeformed (see inparticular FIGS. 12 to 14). In regular operation, preferably loads onthe energy absorption sleeve 98 occur here which exclusively involveforces of less than 750 N.

A load on the energy absorption sleeve 98 with a force of essentiallymore than 3000 N constitutes an overload event for the illustratedembodiment. This causes the energy absorption sleeve 98 to beplastically deformed.

Such an overload event occurs when the spindle nut 28 runs up againstthe stop assembly 96, more precisely the energy absorption sleeve 98, attoo high a speed and/or too high a force.

This may happen, for example, when the hysteresis brake 82 is defective.

An overload event may also occur during installation of the vehicle flap10 when the spindle drive assembly 12 is already connected with thevehicle flap 10, but further components of the vehicle flap 10 are stillmissing. The vehicle flap 10 is then significantly more lightweight thanduring operation of an associated vehicle, for which the spindle driveassembly 12 is designed. In this connection, the spindle drive assembly12 may be transferred to an open position by means of a spring that isnot further specified. Due to the relatively low weight of the vehicleflap, the spindle nut 28 will then run up against the stop assembly 96too quickly.

In all overload events, the energy absorption sleeve 98 absorbs theenergy resulting from the excessive speed and/or excessive force andthereby protects the other components of the spindle drive assemblygroup 12 from damage.

FIG. 14 illustrates the spindle nut 28 resting against the energyabsorption sleeve 98. However, for reasons of greater clarity, thelatter is shown in its plastically undeformed state.

A subsequent operation of the spindle drive assembly 12 in which theopening and closing of the vehicle flap 10 is still possible without anyproblems is also referred to as an overload sequential operation. Inthis operating condition the energy absorption sleeve 98 is plasticallydeformed (not illustrated).

In the event that the energy absorption sleeve 98 comprises a pluralityof deformation portions, only one of the deformation portions isplastically deformed in the overload sequential operation.

In case a second overload event occurs subsequently and the energyabsorption sleeve 98 comprises a second deformation portion, the latterwill deform plastically due to the second overload event. Subsequently,the spindle drive assembly 12 will enter a secondary overload sequentialoperation, in which the opening and closing of the vehicle flap 10 bymeans of the spindle drive assembly 12 continues to be ensured.

1. A spindle drive assembly for opening and/or closing a vehicle flap,comprising a spindle drive assembly housing which extends along aspindle drive axis and comprises, between its axial ends, a stop sectionacting axially on both sides, wherein a motor gear unit is arranged on afirst axial side of the stop section and wherein a spindle unit isarranged on a second axial side of the stop section opposite the firstaxial side.
 2. The spindle drive assembly according to claim 1,characterized in that the spindle drive assembly housing comprises ahousing cap, which closes the spindle drive assembly housing on themotor gear unit side.
 3. The spindle drive assembly according to claim1, characterized in that the motor gear unit is supported in the spindledrive assembly housing so as to be rotationally fixed with respect tothe spindle drive axis.
 4. The spindle drive assembly according to claim1, characterized in that the spindle unit comprises a guide tubefastened in the spindle drive assembly housing.
 5. The spindle driveassembly according to claim 1, characterized in that the stop section ismanufactured in one piece with the spindle drive assembly housing. 6.The spindle drive assembly according to claim 1, characterized in thatthe spindle drive assembly housing is made from a plastic material.
 7. Avehicle flap, comprising a spindle drive assembly according to claim 1.8. A method of assembling a spindle drive assembly for opening and/orclosing a vehicle flap, comprising the steps of: (a) providing a spindledrive assembly housing extending along a spindle drive axis; (b)inserting a motor gear unit into the spindle drive assembly housingstarting from a first axial side of the spindle drive assembly housing;and (c) inserting a spindle unit into the spindle drive assembly housingstarting from a second axial side of the spindle drive assembly housingopposite the first.
 9. The method according to claim 8, characterized inthat a stop section acting axially on both sides is provided at thespindle drive assembly housing and the motor gear unit is placed againsta first axial side of the stop section.
 10. The method according toclaim 8, characterized in that the motor gear unit is mounted in thespindle drive assembly housing in a rotationally fixed manner.
 11. Themethod according to claim 8, characterized in that a stop section actingaxially on both sides is provided at the spindle drive assembly housingand the spindle unit is placed against a second axial side of the stopsection opposite the first axial side.
 12. The method according to claim8, characterized in that the spindle unit is fastened to the spindledrive assembly housing.
 13. The method according to claim 12,characterized in that a guide tube comprised by the spindle unit isfastened to the spindle drive assembly housing.
 14. The method accordingto claim 8, characterized in that a housing cap is placed on the spindledrive assembly housing on the motor gear unit side, so that the housingcap closes the spindle drive assembly housing.
 15. The method accordingto claim 14, characterized in that the housing cap is fastened insidethe spindle drive assembly housing.
 16. The spindle drive assemblyaccording to claim 3, characterized in that the motor gear unit issupported in the spindle drive assembly housing by means of a dampingelement or by means of a plurality of damping elements.
 17. The vehicleflap according to claim 7, which is a vehicle hatch or tailgate orvehicle trunk lid.
 18. The method according to claim 10, characterizedin that the motor gear unit is mounted in the spindle drive assemblyhousing with an interlocking fit.